I have the ruined row of three houses and the ruined row of four houses, from Total Battle Miniatures. Having cleaned the models, I gave the inside of the models a black undercoat and then masked the inside of the windows (with masking tape) before I give the model a white undercoat on the outer side of the model.
I then started on the basecoat of the various parts of the building, for the brown I used a Tamiya acrylic.
I used a thinned coat of paint, as I will be adding a drybrush and some washes.
Once I have finished painted the ruins, I think I will add some additional detrius, broken beams and so on to add a little more detail.